This invention relates to a control and regulating apparatus of a sheet-delivery device, in particular for sheet-processing machines.
With sheet-delivery devices of this kind, the individual sheets which have been processed by the machine in some manner, for example, printed, coated or processed in some other way, are removed from the sheet-processing machine by means of gripper arrays which are mounted on two circulating, mutually parallel chains; then, by way of a row, which row extends transversely with respect to the direction of movement of the sheets, of suction wheels which apply a braking or a lift-off action to each sheet, or by means of a corresponding continuous suction roller, or by another means of applying a braking action, the sheets which have been removed from the machine are braked before they are deposited above a receiving stack, and then deposited on the top of the stack. This operation is effected by the grippers' which guide the individual sheets being opened by means of a gripper-opening cam, and more specifically, the time at which the grippers are opened is adjustable in accordance with certain features and details of the sheets, as set out in detail hereinafter, and also of the machine. For reasons which also depends on the properties of the material being printed and the printing machine, both peripheral speed of the suction wheels (or suction roller) and the increased or reduced pressure applied at the suction wheels or the suction roller are also adjustable.
If hereinafter in this specification, reference is only made to sheet-delivery devices for sheet-fed printing machines, that is intended only to be by way of example in regard to the sheet-delivery devices of other machines for processing sheets or reels. (In the case of reel-processing machines, the web of material, after being printed or the like, can be cut into sheets and also deposited in sheet-delivery devices.) This mode of expression is used only in order for the description to be drafted in shorter and clearer form. However, it is not intended to restrict the scope of the protection claimed to sheet-delivery apparatus for sheet-fed printing machines, but on the contrary, the scope of protection claimed is intended to extend to the delivery and distributing or depositing devices of all machines in which sheets are subject to processing in some manner and then fed out of the machine and deposited or distributed.
In sheet-processing machines, for example, sheet-fed printing machines, precautions in respect of safety and programming are taken for almost all parts or elements of the machine. There are defective-sheet controls, double-sheet controls, sheet-checking operations at the individual printing rolls; there is also programming in respect of printing programs which have already been carried out at the inking mechanisms and at the damping mechanisms; there are controls in respect of premature sheets, retarded sheets and defective sheets; there are side-mark controls; there is the control in respect of sheet transfer from roll to roll and from printing mechanism to printing mechanism; and there are crumple- or crease-sheet safeguards, and many more.
Hitherto, there was nothing of that kind for a sheet-delivery device. The correct setting of the various adjustable elements of a sheet-delivery device involves a whole series of factors, including the quality of the paper (weight of the paper per unit of area); operating speed (rotary speed) of the machine, more specifically during the start-up and shut-down phases, compared with the continuous or steady-state printing operation (for example, a larger number of sheets are printed until the desired operating printing speed is reached); in addition, a part is also played by the format and also the printed image, that is to say, the amount (and thus the weight and distribution) of the ink on each individual sheet. Correct presetting and continuous resetting of the device, for example, when there are changes in the speed of rotation or after any intentional or unintentional stoppage of the machine, which has a whole series of different forms of adjustability, has hitherto been left to the attentiveness, the capability, and the skill of the printer. Until the printer has found the optimum setting for all elements of the sheet-delivery device, more particularly having regard to the large number of possible adjustments and settings available, there may be a considerable amount of wastage, a corresponding loss of material, and a decrease in the overall productivity of the printing machine.
Hitherto, a single and only very partial form of automation of the mode of operation of sheet-delivery devices has been known; more specifically, German Patent specification No. 818,365 discloses that the adjustable cam onto which the gripper arrays holding the sheet pass and are thereby opened, and therewith also the time of opening of the grippers is only one of the many adjustment features of a sheet-delivery device, and, as already indicated, the correct time of opening also depends not just on the speed of rotation of the machine but also on many other influences, factors or parameters.
The problem of the present invention is to avoid the above-indicated disadvantages by providing a novel control and regulating apparatus for a sheet-delivery device, which makes it possible for all settings required in respect of the adjustable elements of a sheet-delivery device to be set in the optimum fashion from a single location, and to be automatically re-adjusted to meet fluctuating conditions in accordance with a predetermined program, and thereby to achieve a very considerable saving in time, to avoid wastage of material, and at least substantially to eliminate dependency on the skill, capability, and knowledge of the printer.
According to the present invention, there is provided an apparatus for control and regulating a sheet-delivery device, with which delivery device individual sheets are removed therefrom by means of gripper arrays mounted on two circulating, mutually parallel chains, and guided above a receiving stack by way of a transversely extending row of suction wheels which apply a braking or a lift-off action to each sheet, or a corresponding continuous suction roller, over which stack the grippers are opened by means of a gripper-opening cam which is adjustable to provide for an earlier or later gripper-opening action, and with which the peripheral speed of the suction wheels or suction roller and the reduced or increased pressure applied thereat and the longitudinal setting of the suction wheels or suction roller are adjustable in the direction of the sheet movement of the purposes of adaptation to different sheet-format lengths, wherein, for altering a plurality of the following values (1) to (7):
(1) the speed of rotation of the suction wheels or suction roller;
(2) the longitudinal setting of the suction wheels or suction roller;
(3) the reduced or increased pressure at the suction wheels or the suction roller and switching same on and off and switching over from suction air to blowing air;
(4) adjustment of a gripper-opening cam for varying the time of opening of the sheet grippers;
(5) the speed of rotation and switching on and off of fans which blow downwardly onto the sheet to facilitate the stacking action, or the pressure of another kind of regulatable blowing sources which have the same action and act at a point;
(6) the pressure at pressure-blast nozzles (rake-like blowing unit) which are optionally provided, for fixing and thrusting the sheet downwardly upon deposit thereof, and
(7) other adjustable elements of the delivery device, such as a stack-level regulating means, or switching over of the straight thruster motion of an individual stroke movement per sheet, to a shaker motion,
there are provided respective separate control motors with feedback of the setting reached to a reference-value-setting means or electromagnetic valves, and wherein the reference-value-setting means is provided with a respective input speed of rotation of the machine, and is connected to or integrated with a computer which computes the reference values for all settings of the feeder, such reference values being determined empirically for each operating condition and being stored in the form of a family of characteristics, said computer outputting said reference values to the reference-value-setting means which transmits same to control motors or electromagnetic valves.
It should be clearly emphasized that the servo adjustment and automatic control or regulation does not have to be provided for all points or values 1 to 7 set forth in the above comprehensive definition of the invention, but that one setting or the other may also be adjusted in conventional manner, while perhaps three or four others of the points specified are automatically controlled or regulated in the manner characterized in the above comprehensive definition of the invention.
The memory and the reference-value-setting means or generator may be a separate element of the machine, which is only associated with the sheet-delivery device; however, they may also be combined with or partially or fully integrated into the computer which is provided in the machine in any case, for example, for the inking-mechanism or damping-mechanism programming and control or with some other computer that is already provided in the machine.
With the reference-value-setting means and/or the computer, there may be provided a memory having interchangeable-memory elements, to which there are connected a first switch which can be switched over from manual setting to automatic setting in respect of the adjustable elements of the apparatus, and a second switch for putting into storage in the memory element the optimum values which are empirically determined by manual setting.
Therefore, in this case also the correct values for the various possible settings of a sheet-delivery device are determined empirically, but the values are then stored and subsequently, when the same printing operation is carried out again, or when a printing operation which is at least fairly similar is performed, those values can be set again by using the memory element which was previously already prepared for that purpose, without the printer's being required to be particularly attentive in that respect. In fact the operation of changing a memory element into a reference-value-setting means requires only a very small amount of time.